University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1987 Creation and performance of music structures Charles J. Zacky The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Zacky, Charles J., "Creation and performance of music structures" (1987). Graduate Student Theses, Dissertations, & Professional Papers. 1933. https://scholarworks.umt.edu/etd/1933 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1976 THIS IS AN UNPUBLISHED MANUSCRIPT IN WHICH COPYRIGHT SUBSISTS. ANY FURTHER REPRINTING OF ITS CONTENTS MUST BE APPROVED BY THE AUTHOR, I^TANSFIELD LIBRARY UNIVERSITY OF MONTANA DATE : 19 87 THE CREATION AND PERFORMANCE OF MUSIC STRUCTURES Charles J. Zacky B.A., University of California, 1974 M.M., University of Montana, 1983 Presented in partial fulfillment of the requirements for the degree of Master of Science University of Montana 1987 Approved by Chairman,Board of Examiners Date UMI Number: EP35196 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI UMMnsnn »-rUDMning UMI EP35196 Published by ProQuest LLC (2012). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 Zacky, Charles J., M.S., Dec. 1987 Computer Science The Creation and Performance of Music Structures (85 + iv pp.) Director: Spencer L. Manlove S OV\ Recent years have witnessed the development of microprocessor-based musical instruments. More recently, a communications specification has been developed allowing these instruments to be networked together. The Musical Instrument Digital Interface (MIDI) specification has resulted in the development of hardware and software systems designed to play and record data generated by these digital instruments. Systems that record and play MIDI data are called sequencers. A musical composition is a hierarchy of structures. Current sequencer technology focuses on the objects at the bottom of the hierarchy, notes and phrases. The design of a composition requires the creation and manipulation of structures at all levels of the hierarchy. Therefore, an effective environment for the development of musical compositions must allow the creation and manipulation of high-level musical constructs. An approach to the definition and performance of music structures is presented. Abstract data structures and operations on them are defined which provide for the creation of music structures. For performance, these data structures are transformed into a tree which more directly represents the hierarchical nature of the music. The tree is traversed during the performance, each node representing a part of the music structure. The contents of a tree node and its attendant operations are defined. An algorithm for traversing the tree during performance is presented. ii Acknowledgments Special thanks to Professor Patrick C. Williams of the Music Department, Jerry Durrin, owner of Bitterroot Music, Philip E. Rosine, and Douglas F. Marsh. This effort is dedicated to my mother and to the memory of my father. iii Table of Contents Abstract ii Acknowledgments iii Table of Contents iv 1 Background 1 2 Music Structure 15 3 Sequencer Structure 29 4 Definition and Performance of Music Structures 4 6 5 Evaluation and Future Enhancements 69 Appendix 80 Bibliography 84 iv Chapter One Background 1.1. Thesis Overview This paper discusses a means to organize and manipulate abstract musical structures and to realize these structures in real-time. Electro-acoustic hardware has evolved from its formative stages. The variety and sophistication of electronic instruments make possible the development of software systems which can concentrate on high-level functions rather than low-level control. The current technological milieu, of both hardware and software, from which this project developed is discussed. A model of musical structure is presented which reflects the hierarchical nature of music and which reflects a constructive approach as used by those who compose music. 1 2 A notation to represent musical structures is introduced and illustrative examples are developed. The sequencer is a tool for recording, manipulating, and performing music. Current trends in sequencer design are examined. A model is presented which is constructed by associating sequencer functions with the various levels of musical structure. A case study examines an existing sequencer in terms of the model presented. The requirements for a compositional tool which provides functions for the creation and manipulation of abstract musical structures is presented. It is examined in terms of its representation of the musical structures previously presented and compared with the sequencer model for functionality. 1.2. Chapter Overview In recent years, microprocessor technology has permeated the electronic music industry, giving rise to a plethora of microprocessor-based devices. Some of these devices are sound producing instruments, others act as controllers or signal processors. The result is that the music technologist of today has music-producing tools of great power available. In response to the development of intelligent instruments, a digital communications 3 specification has been developed which allows dissimilar devices to be interfaced into a single system. This Musical Instrument Digital Interface (MIDI) specification not only provides for the connecting of MIDI-based equipment, but also allows a computer to be part of a MIDI system. 1.3. MIDI Instruments MIDI instruments can be classified into three broad categories; sound generators, controllers, and signal processors. Sound generators are the most familiar MIDI instrument. The sound may be created by one of two methods, synthesis or sampling. A synthesizer contains oscillators which generate periodic waveforms such as sine, square, or triangle waves. These waves are manipulated and combined by other circuitry to produce complex audio signals. A digital sampling instrument is like a digital tape recorder in that it digitizes audio signals directly. In general, a sampler has less sound modification functions than does a synthesizer. Samplers are useful primarily for reproducing existing sounds, whereas synthesizers are more flexible in producing new sounds. There are a great number of synthesizers available. Product uniqueness is partially derived from functionality but more fundamental is the uniqueness of sounds which the 4 synthesizer is able to generate. There are several methods of synthesis currently in use: frequency modulation (FM), additive synthesis, linear arithmetic synthesis, phase distortion, wavetable synthesis, pulse code modulation, subtractive synthesis, and structured adaptive synthesis. Sampling instruments are characterized by the large amounts of memory which must hold digitized audio signals. Two or more megabytes of RAM is not uncommon on low-end instruments with 8 to 50 megabytes1 available for more expensive products. A class of instruments which do not include sound generation capabilities but specialize in sending MIDI data to sound sources are called controllers. As the name implies, they control or drive the devices connected to their outputs. Controllers are played in real-time and usually take the form of traditional instruments. The most common controller is the keyboard controller. Other controllers include guitar controllers, wind controllers which resemble clarinets, and percussion controllers. Related to controllers, in that they do not generate sound directly, are sequencers. Whereas controllers resemble [1] The Fairlight Series III has 50 megabytes of RAM, a 600 megabyte hard disk, a 400 megabyte optical storage and a price tag of $175,000. 5 standard instruments, sequencers can be compared to tape recorders. They store MIDI data for later playback. In addition to recording and playback functions, sequencers offer editing functions. Editing is usually accomplished on two levels, event editing and track editing. Event editing allows modification of individual parameters such as the pitch of a single note. The scope of track-level editing is an entire track. Transposing the pitch of an entire track is an example of a track-level operation. Signal processors are not new to the electronic music field. In the past they were exclusively analog devices but today are primarily digital. Signal processors are effects devices which produce effects such as reverberation, delay, echo, chorus, flange, distortion, tremolo, stereo panning, compression, and equalization. The most common type of MIDI implementation in signal processors is the ability to call up a predefined effects configuration.